JP2803617B2 - Beam-fed double reflector mirror scan antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam-fed double-reflecting mirror-type scan antenna that always keeps the plane of polarization constant.

[0002]

2. Description of the Related Art Conventionally, a beam-fed double-reflecting mirror type scan antenna has been mounted on an aircraft, an artificial satellite, or the like and used for a radar or the like. That is, while rotating the antenna about a predetermined axis, the radio wave is radiated in the [transmission mode],
Receiving the reflected wave in the [reception mode] has been used for measuring the direction and distance from a measurement point to a target object, and the like.

A conventional example will be described with reference to the drawings. FIG.
FIG. 1 is a cross-sectional view and a block diagram showing a conventional beam-fed double-reflecting mirror scan antenna. 1 is a transmitter, 2 is a receiver,
Reference numeral 3 denotes a transmitter 1 and an orthogonal polarization demultiplexer (hereinafter referred to as OMT).
6, a rotary joint (hereinafter referred to as RJ) rotatable around the x-axis with respect to the alternate long and short dash line in FIG. 2, and 4 connects the receiver 2 and the OMT 6. RJ, which is provided in the middle of the waveguide which is rotatable around the x-axis with respect to the one-dot chain line in FIG. 2, 5 is a feed unit composed of the OMT 6 and the primary radiator 7, 8 is a sub-reflector, 9 is a main reflecting mirror. Reference numeral 10 denotes an antenna base provided with the RJs 3 and 4, the power supply unit 5, the sub-reflecting mirror 8, and the main reflecting mirror 9. 11
Denotes a motor, and 12 denotes a gear for transmitting the rotational driving force of the motor 11 to the antenna base 10. In addition, the motor 11 and the gear 12 constitute driving means.

[0004] The operation of the conventional example having the above configuration will be described separately for [transmission mode] and [reception mode]. First, regardless of the [transmission mode] and the [reception mode], the antenna base 10 is always rotated in a predetermined direction by the rotation driving force of the motor 11 being transmitted through the gear 12.

[Transmission mode] A desired radio wave is output from the transmitter 1 and supplied to the OMT 6 via the RJ 3. Note that R
The upper part (above the dashed line) of J3 rotates in synchronization with the antenna, and the lower part (below the dashed line) does not rotate because it is fixed. The OMT 6 excites the supplied radio waves as linearly polarized waves parallel to the x-axis (hereinafter, referred to as V-polarized waves).
The excited radio wave is output via the primary radiator 7 and radiated outside the antenna via the sub-reflector 8 and the main reflector 9. The emitted radio wave is reflected by a target object or the like, and then received by the main reflecting mirror 9 in the [receiving mode].

[Reception mode] The radio wave incident on the main reflecting mirror 9 is reflected by the sub-reflecting mirror 8,
It is supplied to MT6. The OMT 6 demultiplexes only a linearly polarized component (hereinafter, referred to as H polarization) component parallel to the y-axis of the supplied radio wave, and supplies the demultiplexed radio wave to the receiver 2 via the RJ 4. RJ4 is configured similarly to RJ3,
The upper part rotates in synchronization with the antenna base 10, and the lower part is fixed.

[0007]

As described above, in the conventional beam-fed double-reflecting mirror-type scan antenna, since the entire feeding section is rotated together with the antenna base, the plane of polarization is rotated by the rotation of the antenna base. I never did. However, the position of the feeder on the antenna base is limited. That is, since the primary radiator rotates together with the reflector and the transceiver is fixed, there is a problem that the distance between the transceiver and the primary radiator becomes longer and the power supply loss increases. Further, in the rotating portion, the waveguide must be connected via the RJ, and there is a problem that the mounting of the RJ increases the weight. Furthermore, there is a problem that a high degree of assembly accuracy is required to make the rotation axis of the RJ coincide with the rotation axis of the antenna base. An object of the present invention is to solve such a problem, and an object of the present invention is to provide a beam-fed double-reflecting mirror-type scan antenna that does not use any RJ and can always keep the polarization plane constant. I have.

[0008]

In order to achieve the above object, a beam-fed double-reflection mirror type scan antenna according to the present invention splits a radio wave supplied from a transmitter into a linearly polarized wave in a transmission mode. It is composed of a quadrature polarization splitter that splits the supplied radio wave into a linear polarization orthogonal to the transmission polarization and outputs it to the receiver in the reception mode, and is fixed and does not rotate A first power supply unit for variably outputting a phase of a radio wave supplied from the first power supply unit in the transmission mode and outputting a variable frequency of the supplied radio wave in the reception mode to the first power supply unit; A 180-degree phase shifter that outputs a signal and a primary radiator that radiates radio waves output from the 180-degree phase shifter in the transmission mode and outputs the supplied radio waves to the 180-degree phase shifter in the reception mode. A second feeder configured to be rotatable about a predetermined axis. And parts, radio waves supplied from the second feeding portion when the transmission mode radiates to the outside, receives a radio wave of the reflected wave emitted when the transmission mode when the reception mode,
And a reflecting mirror group rotatable about the predetermined axis.
With this configuration, the plane of polarization of the antenna can always be kept constant. In addition, since the power supply unit can be arranged on the rotating shaft, a circular rotating flange can be used, and RJ is not required.

[0009]

Next, details of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view and a block diagram showing an embodiment of the present invention. The same reference numerals as in FIG.
Indicates identical or equivalent parts. 5a is primary radiators 7 and 1
A power supply unit (second power supply unit) that is configured to rotate at a predetermined speed around the x-axis,
And a fixed and non-rotating feeder (first feeder) 14 is provided in the middle of the waveguide connecting the feeders 5a and 5b, and is rotatable only about the x-axis (one degree of freedom). A rotary flange, 15 is a speed reducer for adjusting the rotation speed of the power supply unit 5a, and 16 is a plane mirror. The plane mirror 16, the sub-reflection mirror 8, and the main reflection mirror 9 constitute a group of reflection mirrors.

The operation of the present embodiment having the above configuration will be described in detail. The power supply unit 5a includes the antenna base 1
Rotate around the x axis at a predetermined speed in synchronization with the rotation of 0. However, since the feeding unit 5b is fixed and does not rotate, when the antenna base 10 rotates, the polarization plane of the antenna also rotates. For example, when the θ-degree antenna rotates around the x-axis, the rotation angle of the polarization plane also becomes θ-degree. Also, generally 1
Assuming that the physical rotation angle by the 80-degree phase shifter is β degrees, 1
It is known that the rotation angle of the electric polarization plane of the 80-degree phase shifter is 2β degrees.

Therefore, the rotation of the polarization plane due to the rotation of the antenna base 10 is corrected by the rotation of the electric polarization plane of the 180-degree phase shifter 13 to keep the polarization plane constant. In other words, the rotation angle θ of the polarization plane and the electric polarization plane 2β of the phase shifter 13 may be made equal. Therefore, θ = 2β (1), and β = θ / 2 (degrees) (2).

Thus, when the antenna base 10 is rotated by θ degrees, the polarization plane can be kept constant by rotating the phase shifter 13 in the same direction by β = θ / 2 (degrees). As described above, the feeder 5 a
Is rotated at half the speed of the antenna base 10 to keep the polarization plane constant. Next, the operation of the present invention will be described in detail for [transmission mode] and [reception mode].

[Transmission Mode] The radio wave output from the transmitter 1 is supplied to the OMT 6 to excite the V polarization (H polarization). The excited radio waves are transmitted through the rotating flange 14 to the
It is supplied to the 80-degree phase shifter 13. The supplied radio wave rotates its polarization plane with the rotation angle θ of the antenna base 10, but is returned by the 180-degree phase shifter 13 to V-polarization (H-polarization). Then, the light is output through the primary radiator 7, is reflected in the order of the plane mirror 16, the sub-reflecting mirror 8, and the main reflecting mirror 9, and is radiated to the outside of the antenna.

[Reception Mode] The radio wave incident on the main reflecting mirror 9 is reflected in the order of the sub-reflecting mirror 8 and the plane mirror 16 and supplied to the 180-degree phase shifter 13 via the primary radiator 7. 18
The 0-degree phase shifter 13 changes the phase of the supplied radio wave and supplies it to the OMT 6 via the rotating flange 14. OMT6
Demultiplexes the supplied radio wave into only the H-polarized (V-polarized) component and supplies it to the receiver 2. In the present invention, RJ (a rectangular waveguide and a circular waveguide are combined) is used.
The use of a smaller and simpler rotating flange (constituted by a circular waveguide) reduces the distance between the transceiver and the primary radiator. Therefore, power supply loss is reduced.

[0015]

As described above, according to the present invention, the power supply unit is divided into two parts, and the second power supply unit is provided with a 180-degree phase shifter rotatable around a predetermined axis. Therefore, by rotating the second power supply unit, the plane of polarization of the antenna can always be kept constant. Further, the power supply unit can be arranged on the rotation axis, and the distance between the transceiver and the primary radiator is shortened, so that the power supply loss can be reduced. Furthermore, since it is not necessary to use an RJ, it does not require a high degree of assembly accuracy of matching the rotation axis of the antenna with the rotation axis of the RJ,
It is also possible to prevent an increase in weight due to mounting the RJ.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view and a block diagram showing one embodiment of the present invention.

FIG. 2 is a sectional view and a block diagram showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Transmitter, 2 ... Receiver, 3/4 ... Rotary joint (RJ), 5, 5a, 5b ... Feeding part, 6 ... Orthogonal polarization splitter (OMT), 7 ... Primary radiator, 8 ... Sub Reflector, 9 ...
Main reflecting mirror, 10: antenna base, 11: motor, 12
... gear, 13 ... 180 degree phase shifter, 14 ... rotary flange,
15: speed reducer, 16: plane mirror (mirror).

Claims (3)

(57) [Claims] 1. In a transmission mode, a radio wave supplied from a transmitter is demultiplexed into a linearly polarized wave and output. In a reception mode, the radio wave supplied is demultiplexed into a linearly polarized wave orthogonal to the transmission polarization. And a quadrature polarization demultiplexer that outputs to the receiver.
A first power supply unit that is fixed and does not rotate; and a variable output phase of a radio wave supplied from the first power supply unit in the transmission mode, and a variable phase of the radio wave supplied in the reception mode. A 180-degree phase shifter that outputs to the first power supply unit, and a 180-degree phase shifter that outputs the radio wave output by the 180-degree phase shifter in the transmission mode to radiate to the outside and shifts the supplied radio wave by 180 degrees in the reception mode A second radiator configured to output to the phaser and rotatable around a predetermined axis; and a radio wave supplied from the second power supply unit is radiated to the outside in the transmission mode, and the radio wave is transmitted to the reception mode. And a reflecting mirror group rotatable about the predetermined axis, receiving a reflected wave of the radio wave radiated in the transmission mode and supplying the reflected wave to the second power supply unit, wherein the polarization plane is always kept constant. Beam-fed double reflector mirror scan antenna. 2. The reflecting means according to claim 1, wherein the driving means drives the reflecting mirror group and the second power supply unit to rotate at a predetermined speed, respectively, and the rotation speed of the second power supply unit is half the speed of the reflecting mirror group. A beam-feeding double-reflecting mirror-type scan antenna, comprising: 3. The beam-feeding double-reflecting mirror type scan antenna according to claim 1, further comprising a rotating flange for connecting the first power supply unit and the second power supply unit.